Fusible fastener



patented Jan. 19 1954 wat UNITEDYSTATES @TENT GFFICE f FUSIBLE FASTENER Donald R. Ruegsegger, St. Clair Shores, Mich. Application September 26, 1951, Serial No. 248,430

Claims. Cl. 169-42) This invention relates to fusible links of the type used to hold automatically closable` re doors, automatic fire extinguishers and the like so that these devices kare operated upon a rise in the ambient temperature.

In the past, fusible links of this type have been provided which comprise two fiat plates which are sweat-soldered together with a low meltingpoint solder, each of these plates being secured to one end of the structure so that the solder is subjected to a shearing stress. Upon a rise in ambient temperature the solder will melt, allowing the plates to pull apart. This construction has several disadvantages which limit its usefulness. For one thing, the plates are liable to be subjected to forces transverse to their planes, thereby subjecting the solder to a peeling or tearing action which may easily tear the bond when it is not desired to do so. Furthermore, it is necessary in such a construction to provide a relatively large area, so that suiiicient solder is present to prevent movement under normal conditions.

It is an object of the present invention to overcome the disadvantages of previous constructions and to provide an improved fusible link construction which is extremely simple and economical to fabricate and which obviates the danger of subjecting the sweat-solder bond to other than direct shear stresses.

It is another object to provide an improved fusible link of the above character which usesl parts of a less massive nature than has previously been possible, the joint area provided by these parts being substantially greater for the size of the parts.

It is also an object to provide an improved fusible link of this type which incorporates novel gripping or engaging members for the parts to be held, these engaging members permitting a full swiveling action with relation to the link elements, thereby preventing unwanted torsional or other forces on these elements.

It is a further object to provide an improved fusible link of the abovev nature in which'the parts have an extremely slight mass and are thin walled, thereby enabling the heat to be absorbed over a relatively larger area, increasing the sensitivity of the device.

Other objects, features and advantages of the present invention will become apparent from the subsequent description taken in conjunction with the accompanying drawings.

In the drawings: Y

Figure 1 is a side elevational view of the im- 2 proved fusible link, showing the hook elements for connection to the parts to be controlled;

Figure 2 is a cross-sectional View taken along the line 2-2 of Figure 1 and showing the construction of the link elements;

Figure 3 is a cross-sectional view taken along the line 3 3 of Figure 1 and showing the attaching means for the hooks; and

Figure 4 is a view similar to Figure l but showing the parts in their separated condition.

The invention comprises, in general, a pair of link elements which comprise two hollow cylindrical members,` such as conventional brass eyelets or the like. These elements are normally in telescoped relation and their surfaces are connected by such means as sweat-solder having low melting point. Attached to the outer ends of these tubular elements is a pair of hooks or y similar fasteners, these hooks being preferably y shearing stresses, preventing failure of the link by peeling or tearing. The thin-walled eyelets are subjected to ambient temperature from both the inside and the outside because of their tubular nature, so that, upon a predetermined rise in ambient temperature, the forces on the hooks will cause the links to separate, operating the mechanism.

Referring more particularly to the drawings, the link elements comprise a pair of hollow tubu lar members H and l2, member Ii having a diameter slightly larger than member Iii, so that it can be telesooped thereover. These elements, for example, may comprise thin brass bushings Vor eyelets and may, if desired, be of standard or conventional design. As is best seen in Figure 2, the elements H and I2 are partially telescoped and are joined by a sweat-solder connection i3, this solder having a known low melting point.

The outer ends of elements Il and i2 are provided with radial flanges I4 and i5, respectively, these flanges extending outwardly. The flanges are adapted to retain a pair of engaging hooks I6 and I'I and, in particular, these hooks are provided with circular mounting portions i3 and I9, respectively, for retention by these flanges, as seen in Figure 3. The construction is such that these hooks are allowed a swiveling action with respect to the elements II and I2. The outer ends of hooks IB and I1 are looped to provide engaging portions 2| an-d 22, respectively. The hooks are thus adapted to engage a pair of relatively movable members 23 and 24. For example, member 23 may be connected to a fire door mounted on an inclined track and element 24 to a .stationary portion of the surrounding structure, so that a constant pulling force is present, tending to separate members 2-3 and 24.

The operation of thedevice Iwill be apparent from the foregoing discussion. Normally, the sweat-solder joint i3 will be subjected to a direct' shearing stress due to the constant separating force between members 23 and 24. It-is' also apparent that under no circumstances canthis.-

solder joint be subjected to torsional or other transverse stresses, since the telescopedl nature of elements II and I2 inherently prevents such. stresses from being applied. Furthermore, the swivel nature of the connection between hooks Iii` and I'I and the link will prevent torsional stresses in' the connection from occurring. The link will be subjected toambient temperature both upon its outer surface 25 and its inner surface 2F, since the link has-a continuous annular shape, The relatively thin' walls of elements II and I2 will quickly transfer any rise' in ambient temperature tothe solder connection I3. When this ambient temperature'reaches the melting point of the'solder, the elements Il" and- I2 will instantaneously be pulled apart, as shown in Figure 4, allowing the attached mechanism to operate. solutely no obstruction to the movementfof'these elements, and that all parts of'the solderedjointV will reach the predeterminedV temperature at the same time.

While it will be apparent r that the preferred embodiment of the invention hereindisclosed` is well calculated to fulfill the objects`` above stated, it will be appreciated that the invention is-subject to modification, variation and change without departing from the properl scope or. fair meaning of thesubjoined claims.- For example,

it is apparent thatthe cross-sectionalt shape of" the link elements need not necessarily bev circular but may be of'rectangular,I polygonal or similar shape within the principles of the. invention.

What is claimedis:

l. ln a device of the.` class describedV ai pairv of relatively thin sheet metal tubular elements' in telescopic relation and adaptedv tobe subjected to an axialv force tending. to separate them,l

and a fusible joint connecting the facingsur'- faces of said tubular elements, said joint being subjected to a direct shear stress/by said axial force. v

2. In a device of the classY described, aV pair of open-ended tubular sheet metal elements in telescopic relation, attaching means on each of said elements and adapted to engage' relatively movable outside members',.anc1' a fusible joint connecting the adjacent surfaces of said tubular elements to resist said movement.

3. A fusible link, comprising inner and outer open-ended tubular sheet metal elements in telescopic relation, a fusible metal joiningV the facing surfaces of said elements, and. attaching means swivelly mounted on each of said elements, said attaching means being adapted to engage two relatively movableelementsg. whereby' saidr tubular elements arel subjected to a separating force.-

It will be observed that there is ab- 4. A fusible link, comprising inner and outer tubular sheet metal elements in telescopic relation, a fusible metal connecting the facing surfaces of said elements, a radial flange at the outer end of at least one of said elements, and attaching means on each of said elements and adapted to connect said link between two relatively movable members, at least one of said attaching means comprising a portion over-engagingvsaid ange and rotatable about the axis of said tubular elements without preventing flow of air into the interior of said elements, whereby said one attaching means is swivelly mounted to its tubular element.

5; A` fusible link, comprising inner and outer tubularA sheetV metal elements in telescopic relation, a fusible metal connecting the facing surfaces of said elements, a radial flange at one end of each of said elements, and attaching means for connecting said link between two relatively movable parts, said attaching means comprising a pair of wire hooks havingl bent portions disposed behind said flanges, whereby said hooks are swivelly'mountedlon said tubular elements.

6. A fusible fastener comprising a pair of tele-1 scopically interfittedl tubular elements, a fusible joint connecting the facing surfaces of said tubular elements, portions of at least one of' said' elements defining an opening extending into the interior of the inner one of said elements, and

means for connecting tensioning members to said elements wherebythey may be pulled apart axially in the event of fusing'of said joint.

'7.' A fusible fastener comprising alpair ofrela-V tively thin sheet metal elements, each of' said elements having an inner'fa'ce and an outer face, said elements being nestedlyintertted'with one another and having an inner face of one element adjacent to'an outer face ofthe other element, a layer of fusible joint material between the adjacent faces and holding said elements together, and a coupling portion for connecting a held part to each of said elements.

8. A fusible fastener comprising aV pair of'relatively thin sheet metal elements, each of said'- elements having an inner face and an outer face, said elements being nestedly interttedwith one another and having an inner face of one element adjacent to an outer face of the other element, aV layer of fusible joint materialbetween the adjacent faces and holding saidV elements together, the other faces of said elements being exposed'l to the atmosphere, and al coupling portion for connecting a: held' part to each of said elements.

9. A fusible fastener comprising a pair of relativelyk thin sheetY metal elements, each ofi said elements'having an inner face andan' outer face, saidf elements being nestedly interfitted'with one anotherl andl having an inner face ofone' element adjacent to an outer face ofthe other element, a layer of fusible joint material between the adjacent faces and holding said elements together, and acoupling portion for connecting aV held part to each of said elements,v said coupling portions being spaced longitudinally with respect to said layer.

10; A fusible fastener comprising a pair of relatively thin sheet metal elements; each of said elements having an inner face'and an outer face, said elements being nestedly intertted with one another and having anr inner' face of` one element adjacent to an outer face'of the other element, a layer of fusible joint materialY between the adjacent faces and holding said elements together, the other faces of said elements being exposed to the atmosphere, and a coupling portion for'connecting a held part to each of said elements, said coupling portions being spaced longitudinally with respect to said layer.

DONALD R. RUEGSEGGER.

References Cited in the le of this patent Number 6 Name Date Rockwood Feb. 2, 1909 Goldthwat June 15, 1909 Stephens Aug. 5, 1913 Leonard Dec. 30, 1913 Loepsinger Nov. 17, 1914 Belknap Apr. 3, 1934 

